#字符串不能嵌套

# str1 = "12,234,34,545,676,77,8,"hhhhh",rr"
#字符串不能修改值
str2 = 'erwer'
str2[0]='2'#不能修改
print(str2)#str' object does not support item assignment

str1 = "12,234,34,545,676,77,8,'hhhhh',rr"#依旧是一个单层的结构
# str3 = '12 Nihao  hhhh 'nihao' nibbb'
str4 = '12 Nihao  hhhh \'nihao\' nibbb'##依旧是一个单层的结构
